Machine-switching telephone-exchange system



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R. L. STOKELY MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM 0&1. 3o, 1923.

-Ifiled Dec. 8. 1920 mul 1 WMM Flr. .d mn L.. E, UU QQ Oct. 30 1923.

' R. L. STOKELY MACHINE swITcHING TELEEHONE EXCHANGE SYSTEM Filed D80.8.. 1920 3 'Sheets-$11661;-2"'A /M Ven/ar.- /My L S/oke/y..

Oct. 30, 1923.. 1,472,561 R. L. STOKELY MACHINE SWITCHING TELEPHONEEXCHANGE SYSTEM Filed Dec. 8, 1920 5 sheets-Sheet s A E A U .IQ JUllmruwll. W@ bwl- (EV, f. uw www F Smid@ v h. D Y E TEEU L Wil w n k v,Ww v A QE m@ m. mw Mw llll.. nu. i DUN/wmv W m n,

Patented ct. 30, 1923.

L GFF!V PATE-Nr RAY L. STOKELY, OF FLORAL PARK, .NEW YORK, ASSIGNOR TOWESTERN ELECTRIC COIJIPANY, INCORPORATED, OF VNEW' YORK,

N. Y., CORPORATION OF NEW-YORK.

MACHINE-.SWITCHING TELEPHONE-EXCHANGE SYSTEM.

Application led December 8,.'1920. Serial No.7429,164.

To all whom t may concern.'

` Be it known that I, RAY L. S'roKnLY, a citizen of the United States,residin at Floral Park, in the county of Nassau, State of New York, haveinvented certain new and useful improvements in Machine- SwitchingTelephone-Exchange Systems, of which the following is a full, clear,concise, and exact description.

This invention relates to telephone exchange systems employing machineswitching and its object is to provide an improved circuit arrangementto take care of toll calls.

It is now the practice so far as applicant is aware, in case anautomatic subscriber desires a toll call, for him to set up a connectionover one or more selectors to a recording operators position and giveher the necessary information. This operator passes the information to atoll operator who has access to what are known as toll switches withwhich is associated the necessary long 4distance transmission equipment.The toll operator then selects the calling line by means of these tollswitches, and causes the connection to be built up over toll lines tothe distant exchange wherein the called line terminates. The selectorswhich the calling party used in connecting his line with the recordingoperators position are thus not used in the long distance connectionbetween the subscribers. l

This invention provides an arrangement wherein the switches used by thecalling party in connecting his line with the recording operator-sposition may be used in the long distance connection between thesubscribers, thus obviating the necessity of the toll operator settingup a connection to the calling line.

In accordance with this invention, the trunks terminating at therecording operators position and which are selectable by the callingsubscriber from a certain levelof a selector are provided with longdistance transmission equipment and also terminate at a. toll operatorsposition. A call extended to one of these trunks lights a. lamp at therecording operators position. This operator extends the calling line toa cord at her position and connects lier head set to the cord and thusto the seized trunk and ascertains the wants of the calling subscriber,whereupon the subscriber may restore his receiver,

.station loop, ring yside of .armature closes the switches beingv heldset under control offr the recording operator. This operator may nowcommunicate over an order wire with anoutwardhtoll operator at whoseposition the seized trunk also appears, and pass along to such aaaoperator the required information` The toll operator now connects atollcord j circuit to the terminal of the seized trunk" appearing at herposition, which causesva disconnect signal to be given the recordingoperator who thereupon disconnects theVv trunk fromher position, the setswitches being now controlled by the toll operator. When the recordingoperator passes the call to ythe toll operator, if the calling party is.

on a party line, she presses one of a number of keys which connects theproper character of ringing current to the contacts of a relay, which'relay is operated by the toll operator to signal the originatingsubscriber when she has received a response from the distant subscriber.The extension of the calling line to al toll cord by the tollvoperatoroperates a relay tocut off the trunk from its terminals at the recordingoperators position, leaving between the toll position and thecallingline the long 'distance transmission equipment whichV isfincludedin the trunk which the calling subscriber selected.

Referring to the drawings,V Fig. l illustrates a calling line, a linelswitch, and a selector; Fig. 2 illustrates a recording trunk.A a tolloper` lThe invention will be more readily under stood from a descriptionof the operations involved in setting up a connection. The subscriber:at substation A in making a call closes the following circuit tooperate the line switch LS to seize an idle first selector FS; freepoleof battery, slow relay'lOO, `contact 101, tip side of the line, the sub-102 to ground. Relay 100 in attracting its acircuit for the pulldownwinding 103 of cuit for the'holding winding 104 ofthe line switch,'andin attracting its lower armature the line, contact.

the line s witchwhich in the well-known manner. operates the lineswitch.

iio

prepares a circuit for the vertical magnet 105 oi the first selector.Whilelthe circuit or" the line relay`100 over the substation loop isopened when the line switch operates, this relay isslow to release andholds the Vpull down coil'103 magnetized until after relay F1 operatesand closes the circuitV ot the holding winding 104, ein the Vwell-knownmanner thus maintaining the line switch operated. rlhe calling party nowoperates his sender S for the tirst digit ol' the code Ynecessary tocall a recording operator thus interrupting the circuit of the impulserela-y E1. Each time relay E1 retracts its armature, an impulse istransmitted to the vertical magnet 105 in series with the slow relay G1to lift the brushes of the first selector to the level correspondingtothe digit in question. When the sender restoi'es, relay E1 remainsenergizechand, consequently relay G1 releases. Whenrelay G1 operatedupon the first impulse it prepared a circuit for relay H1 which wasclosed over oft' normal contact 106 on the first step of the selectorshaft.-

This relay thereupon locked up over the tol# lowing circuit: free poleof battery, relay H1, conductor 107, contact 106, conductor V114:,armature and back contact of rot-ary magnet 108, uppermost armature andfront contact of relay H1, conductor 109 to ground at the lowermostarmature of relay D1. Vhen the slow relay G1 releases at theterminationV of the impulses, rotary magnet 1081s energized over theinner armature of relay H1, normal contact of relay G1, Vupper armatureand front contact of relay F1 to ground and rotates theset of br-ushesontoY thefirst trunk. At the end of the stroke of the rotary magnet, thelocking vcircuit ot relay H1 is opened, which relay in releasingreleases magnet 108. The brushes are now in engagement with the firsttrunk in the selected group It this trunk is busy, a ground is presenton the test multiple 110 and this ground is transmitted over the testbrush 111, conductor 112, uppermost armature and back contact ot relayD1, conductor 113, armature and back Contact of the rotary magnet,conductor 114, contact 106, re

lay H1, tree pole` of battery.` Relay H1 thereupon operates and-again'locks itself over the circuit previously traced to ground at thelovvermost armature and back contact of relay D1. In attracting itslower armature, relay H1 again energizes the rotary magnet which rotatesthe brushes on to the next trunk. Assuming this trunk to be idle, noground is presentr on the test multiple 110 and consequently relay H1remains deenergized, after its locking circuit is opened by magnet 108.Switching relay D1, however, is now operated over the following circuit:free pole of battery, relay n.

H1, conductor 107, contact 106, conductor 114, armature and back contactof magnet kground from the upper armature ot relay F1, the vuppermostarmature of relay D1,

conductor V112, Vbrush 111 to the test multiple of the seized trunk tocause the saine to test busy to other selectors. Relay D1, in attractingits inner armatures, extends the tip and ringconductors of the callingline to the tip and ring conductors of the `trunk which terminate in thetalking'brushes 118 and 119. The tip, ring and sleeve conductors on thelett of F ig. 2 are shown dotted, which indicates the omission'. of aselector or selectors. ln practice the trunk shown in Fig. 2,`wouldpreterably terminate in a level oit a third selector andthe subscriber,therefore, will dial a code of' three digits to secure one of the trunksshown in Fig. 2, or in other words to secure a recording operator.Assuming now that the calling line has been extended to an idle trunkshown in Fig. 2, relay 200 thereat operates over the calling linecircuit, and in attracting its lett armature energizes a slow relay 201.Relay 201 in attracting its lett armature applies ground to the sleevewire 202 to maintain the cut-oit winding 101 ot theline switch andswitching relay D1r energized to prevent premature release in `thewell-known manner. Relay 201 at its right armature applies tone from thesource 203 to the calling line to indicate to the calling subscriberthat his call is being .properly extended. Relay 200 in attracting 4itsright armature, lights the calling lamp this lamp, the recordingoperator insertsV the ,plug 400 in the jack 205 which causes .theoperation of relays L101, 206 and 207.

Relay 101 in operating energizes relay 402 whicliextends the callingline to the operators telephone circuit through the normal contacts oickey L103. Relay 20G in operating applies ground to the sleeve wire 202to hold the line switch and selectors set, thus placing the control otthe release ot these switches under the lioint control of the callingparty and the recording operator. Relay 207 in attracting its middlearmature locks itsell2 to the grounded sleeve wire 202. ln attractingits innermost armature this relay ertinguishes the calling lamp 204.-.In attracting its outermost armature, this relay disconnects the ringingtone from the calling line. thus informing the calling sub scriber thathis call has been answered by the recording operator. The recordingoperator may now listen for a tone from the ,tone .coil 130 individualto the class of lines l armature 217 of relay 211.

l such approval.

to which calling line belongs to indicate to her the class of service towhich the calling subscriber is entitled. The tone circuit may be tracedas follows:r free pole of battery, secondary winding 120 of the tonecoil, holding winding 104 of the line switch, line switch contact 122,uppermost armature and front Contact of relay D', sleeve conductor 112,brush 111, multiple 110, upper winding of tone Vtransformer 208 toground at the left armature and front contact of relay 201. This t-oneis transmitted by induction over the following circuit to the operatorsheadset; left side of the lower Winding of the coil 208, conductors 209,210, tip of the jack 205, tip of the plug 400, upper armature and frontcontact of relay 402, normal contacts of key 404, condenser 405, normalcontact of key 403 through the operators te-lephone set, normal contactof key 403, condenser 406, normal contact of key 404, ring of plug 400,ring of jack 205, normal contact of relay 211, condenser 212,retardation coilr 213 to the other side of the lower winding of the tonetransformer 208. It will be understood that the character of Vthe toneor the absence of tone will indicate to the recording operator to whichclass the calling line belongs. Depending upon t-he information thusacquired, ,the operator will either refuse toll service to the callingsubscriber or may give him toll service after approval by a supervisor,or may give him toll service without The recording operator will newdepress key 214 which causes the tone to be removed and connects thetrunk conductors 224, 225 through to her headset, in order that she maycommunicate with the calling party. The operation 'of key 214 energizesrelay 211, which attracting its inner armatures extends the tip and ringconductors of the trunk to which the calling line is now extendedthrough to the tip and ring conductors of the jack 205 in which the plug400 is inserted as described. The attraction of the armature 216 ofrelay 211 releases relay 206, but before relay 206 releases, anotherground is applied over conductors 245, 246. to the sleeve wire 202 byRelay 211 in attracting its armature 216 locks up to the sleeve wire 218now connected to battery through the relay 401. The recording operatornow talks with the calling subscriber and secures from him the necessaryinformation as to the line desired as well as his own number. She nowcommunicates over an order wire (not shown) with an outward tolloperator while retaining plug 400 in ack 205. The outward toll operatornow inserts plug 300 into ack 220. This jack is also individual to thetrunk shown in Fig. 2, but appears at the toll operators position. Theinsertion of plug 300 into jack 220 oprelay 221, arma-ture and 'frontcontact ofY relay 211, trunk conductor 210, 'tip of jack 205, tip of theplug 400, upper armature of relay 402, normal contact .of key 404, lowerarmature of relay 402, relay 408, normal contact of key 404, lowertalking conductor, ring of the plug 400, ring of the jack 205,

lower talking conductor, armatures and front contacts of relay 211 and221 to the other pole of the battery. thus flashes the lamp 409 toindicate to the recording operator that the toll operator has pluggedinto the trunk, whereupon the recording operator removes the( plug 400from the jack 205. The operation of the relay 221 disconnects thetalking conductors 224 and 225 from the talking conductors 226 and 227leading to the jack 205,'The attraction of the uppermost armature ofrelay 221 and the releasing of relay 211 due to the withdrawal of theplug 4,00 from the jack 205 again operates the relay 206 to maintainground on the sleeve wire 202 to prevent release. Thus the control oftherelease is Relay 40s.

now jointly controlled by the subscriber and the toll operator.

The toll operator now proceeds to build up the connection tothe desiredline over the plug 301 and jack 307. The circuits involved are not shownsince they are well known. When the operator at the` distant exchangehas secured the desired party she rings back on the toll line 360, 361which operates alternating current relay 362. This relay opens thecircuit of a slow relay 363 which relay as well as sleeve relay 367 wasoperated when the plug 301 was insertedin iack 307. Relay 363 inreleasinglights lamp 364. The toll operator observing the lighted lampknows that the toll call has been'built up and proceeds to signal thesubscriber at sub-station A who originated the call, by actuating herringing key 305 which operates the alternatingv current relay 240 in'the trunk, Figure 2. This relay in operating opcrates relay 227, whichin turn in attracting its armatures applies ringing current to thecalling line to ring the bell at the calling substation to inform thesubscriber that the party he desires has responded. Tt will beunderstood that in the meantime substation A is not .selectable in thelocal connector multiples due to the ground applied by way les of wire112, to the connector multiple in accordance with standard practice. There moval ofthe receiver by the originating subscribe-r again operatesrelay 200, which re moves battery and ygroundV from the trunk conductors2211- and .225, releasing the relay 802 in the toll cord, Figure 3. rlherelease ot this relay extinguishes the lamp 303 thus informing the tolloperator that the subscriber has removed his` receiver. T scribers maynow converse. Talking current is ted to the substation ot theoriginating subscriber over the windings otrelay 200 and repeating coil228. Talking current is fed to the distant station trom the otfice inwhich such station terminates, through the windings of a similarrepeat-- ing coil, in accordance with standard long distance practice.

The calling subscriber upon the termination of the conversation replaceshis receiver. This causes the relay 200 to close its back contacts;again applying battery and ground to the trunk conductors 224 and 225 tooperate the relay 302 in the toll cord, which relay in operating againlights the lamp 303 to serve as a disconnect signal to the tolloperator, whereupon she removes the plug 300 from the jack 220 and bymeans of her ringing key 306 rings out on the toll line 360, 361 to givea disconnect signal to the distant operator.

Removal of the plug 300 from the jack 220 releases relay 221 whichreleases relay 200.` Relay 206 in retracting its armature, removesground trom rLthe sleeve conductor 202 thus causing the release of theline switch and the selectors. The release oi` relays 221 and 20'?restores the normal connection o1c the trunk 224C and 225 with the jack205 atthe recording operators position,

Three relays 230, 231. and 232 are shown and keys 233, 23a and 235 areprovided for party line working to permit the recording operator to pickout the particular character of ringing current required, and prepare acirc-uit for impressing such current on the originating subscrihersline, which circuit is closed, by the toll Operator as described. 7lheoperation ot any ot these keys operates the corresponding relay whichthereupon locks up through a key 241 to ground on the sleeve wire 202,the operated relay connecting the proper generator to the iront contactsof the relay 250 which is operated when the toll operator actuates herringing key 305 to signal the calling party when the distant calledparty has answered. The key 241 is provided to restore the setting ifthe operator has pressed the wrong key.

di hat is claimed is:

1. in a telephone system, lthe combination of subscribers lines, a trunkline having long distance transmission equipment included therein, twopositions at each of which said trunk terminates, a signal for saidtrunk at one of said positions, automatic switches tor extending asubscribers line to said trunk, means for thereupon operating saidsignalv` a cord circuit at the posihe suby tion where the signal islocated, mea-ns for associating thevsaid cord circuit with said trunk, acord circuit at the other position,

means for associating the same with said trunk and automaticallydisconnecting the first cord circuit therefrom, and means controlledfrom said other position :for extending the call in the direction of thedesired line.

2.1ln a telephone system, the combination of subscribers lines, a trunkline having long distance transmission equipment included therein, twopositions at each of which said trunk terminates, a signal tor saidtrunk at one ot said positions, automatic switches Jfor extending asubscribers line said trunk, means for thereupon operating said signal,a cord circuit at the position where the signal is located, means forassociating the said cord circuit with said trunk, a cord circuit at theother position, means tor associating the same with said trunk andautomatically disconnecting the iirst cord circuit therefrom and fortransmitting a disconnect signal to said first position, and meanscontrolled from said other position for extending the call in thedirection of the desired distant line.

3. ln a telephone system, the combination of subscribers lines, a trunkline having long distance transmission equipment included therein,recording operators position wherein said trunk terminates, a tolloperators position wherein said trunk also terminates, a signal at saidrecording operators position for said trunk, automatic switches forextending a suhscribers line to said trunk, means i'or thereuponoperating said signal, a cord circuit at said recording operatorsposition, means for associating the same with said trunk, a cord circuitthe toll operators position, means for associating the same with saidtrunk, and means actuated thereby Jfor disconnecting the trunk from therecording opcrators position and for giving her a disconnect signal.

Ll. ln a telephone system, the combination orn subscribers lines, atrunk line having long distance transmission equipment included therein,a recording operators position wherein said trunk terminates, a tolloperators position wherein said trunk also terminates, a signal at saidrecording operators position tor said trunk, automatic switches forextendinc` a subscribers line to h said trunk, means tor thereuponoperating saic signal, cord circuitat said recording operators position,means for associating tne same with said trunk, a cord circuit at thetoll operators position, means tor associatingthe same with said trunk,means actuated thereby for disconnecting the trunk from the recordingonerators osition and KD AL ter giving her a disconnect signal, andmeans controlled from the toll position for extending the call in thedirection of the desired distant line.

5. In a telephone system, the combination of subscribers lines, a trunkline having long distance transmission equipment included therein, arecording operators position wherein said trunk line toll operatorsposition wherein said trunk line also terminates, a signal at saidrecording operators position for said trunk, automatic switches forextending a subscribers line to said trunk, means for thereuponoperating said signal, a cord circuit at said recording operatorsposition, means for associating the same with said trunk, a plurality ofsources of ringing current, keys controlled by said recording operatorfor preparing the circuit to associate one of said sources with saidtrunk, a cord circuit at the toll operators position, means forassociating same with said trunk, means actuated thereby fordisconnecting the trunk from the recording operators position and forgiving her a disconnect signal, and means controlled by the tolloperator for closing said prepared ringing circuit.

6. In a telephone system, the combination of subscribers lines, a trunkline having lon@ distance transmission equipment, included therein, arecording operators position wherein said trunk line terminates, a tolloperators position wherein said trunk line also terminates, a signal atsaid recording operators position for said trunk, automatic switches forextending a subscribers line to said trunk, means for thereuponoperating said signal, a cord circuit at said recording operatorsposition, means for associating the same with said trunk, a source ofringing current, a key controlled by said recording operator forpreparing the circuit to associate said source with said trunk, a cordcircuit at the toll operators position, means for associating same withsaid trunk, means actuated thereby for disconnecting the trunk Jfrom therecording operators position and for giving her a disconnect signal, andmeans controlled by the toll operator for closing said prepared ringingcircuit. Y

7. In a telephone system, the combination of subscribers lines, a trunkline having long distance transmission equipment included therein, arecording operators position wherein said trunk terminates, a tolloperators position wherein said trunk also terminates, a signal at saidrecording operators position for said trunk, automatic switches forextending a subscribers line to said trunk, means for thereuponoperating said signal, a cord circuit at said recording terminates, a.v

operators position, means for associating the same with said trunk, tonesources associated with the calling lines, a circuit including thecalling line source, and said cord circuit closed when the cord circuitis associated with the trunk, a key for opening said circuit, a tonesource associated with the "trunk, a circuit including said source andthe callingline which is closed when the calling line is extended toIsaid trunk, means yactuated by the operator in responding to the callfor opening said last tone circuit, a cord circuit at the toll operatorsposition, means for associating the same with said trunk, and meansactuated thereby for disconnecting the trunk from the recordingoperators position and for giving her a disconnect signal.

S. In a telephone system, the combination of subscribers lines, a trunkline having loncr distance transmission equipment incluc ed therein, arecording operators position wherein said trunk terminates, a tolloperators position wherein said trunk also terminates, a signal at saidrecording operators position for said trunk, a line switch and aplurality of selector switches adapted to be set by the callingsubscriber to select said trunk, means for thereupon operating saidsignal, means controlled by the calling subscriber for releasing saidswitches, a cord circuit at said recording operators position, means forassociating the same with said trunk, and for transferring the controlof release of said switches to the operator, a cord circuit at the tolloperators position, and means for associating the saine with said trunkand for transferring the control of the release of said switches to saidtoll operator and for disconnecting the trunk from the recordingoperators position and for giving her a disconnect signal.

9. In a telephone system, the combination of subscribers lines, a trunkline, two positions at each of which said trunk terminates, y

a signal for said trunk at one of said positions, means for extending asubscribers lineto said trunk and operating said signal, a connectingcircuit at the position where the signal is located, means forassociating said connecting circuit with said trunk, a connectingcircuit at the other position, means actuated by the association of thesecond connecting circuit with said trunk for disconnecting the firstconnecting circuit therefrom, and means controlled from said otherposition for extending the call in the direction of the desired line.

In witness whereof, I hereunto subscribe my name this 2nd day ofDecember A. vD.,

